共查询到20条相似文献,搜索用时 15 毫秒
1.
I. Van Nerum A. C. Certal M. M. Oliveira J. Keulemans W. Broothaerts 《Plant cell reports》2000,19(11):1108-1114
Many flowering plants contain stylar S-RNases that are involved in self-incompatibility and S-like RNases of which the biological
function is uncertain. This paper reports the deduced amino acid sequence of an S-like RNase gene (PD1) from the self-incompatible plant Prunus dulcis (almond). The amino acid sequence of PD1, which was derived from cDNA and genomic DNA clones, showed 34–86% identity to acidic
plant S-like RNases reported so far, with the highest degree of similarity being to an S-like RNase from Japanese pear (Pyrus pyrifolia). Based on RNA hybridisation experiments it appears that, like for many other S-like RNases, the expression of PD1 is not
pistil-specific. Analysis of the genomic structure revealed the presence of three introns, of which one is similar in location
to that of the related S-RNase gene from Solanaceae and Rosaceae. At least four bands hybridising to PD1 were found upon Southern
hybridisation, suggesting the presence of a multigene family of S-like RNase genes in almond. The putative biological function
of PD1 is discussed.
Received: 22 November 1999 / Revision received: 18 February 2000 · Accepted: 13 March 2000 相似文献
2.
Factors affecting Lactobacillus fermentation of shrimp waste for chitin and protein liquor production were determined. The objective of the fermentation
is medium conditioning by Lactobacillus through production of proteases and lowering of the pH. The efficiency was tested by conducting fermentation of biowaste
in 1-l beakers with or without pH adjustment using different acids. Addition of 5% glucose to the biowaste supported the growth
of lactic acid bacteria and led to better fermentation. Among four acids tested to control pH at the start and during fermentation,
acetic acid and citric acid proved to be the most effective. In biowaste fermented with 6.7% L. plantarum inoculum, 5% glucose, and pH 6.0 adjusted with acetic acid, 75% deproteination and 86% demineralization was achieved. Replacement
of acetic acid by citric acid gave 88% deproteination and 90% demineralization. The fermentation carried out in the presence
of acetic acid resulted in a protein fraction that smelled good and a clean chitin fraction.
Received: 4 April 2000 / Received revision: 9 June 2000 / Accepted: 9 June 2000 相似文献
3.
Trihydroxy unsaturated fatty acids with 18 carbons have been reported as plant self-defense substances. Their production in
nature is rare and is found mainly in plant systems. Previously, we reported that a new bacterial isolate, Pseudomonas aeruginosa PR3, converted oleic acid and ricinoleic acid to 7,10-dihydroxy-8(E)-octadecenoic acid and 7,10,12-trihydroxy-8(E)-octadecenoic acid, respectively. Here we report that strain PR3 converted linoleic acid to two compounds: 9,10,13-trihydroxy-11(E)-octadecenoic acid (9,10,13-THOD) and 9,12,13-trihydroxy-10(E)-octadecenoic acid (9,12,13-THOD). Stereochemical analyses showed the presence of 16 different diastereomers — the maximum
number possible. The optimum reaction temperature and pH for THOD production were 30°C and 7.0, respectively. The optimum
linoleic acid concentration was 10 mg/ml. The most effective single carbon and nitrogen sources were glucose and sodium glutamate,
respectively. However, when a mixture of yeast extract (0.05%), (NH4)2HPO4 (0.2%), and NH4NO3 (0.1%) was used as the nitrogen source, THOD production was higher by 8.3% than when sodium glutamate was the nitrogen source.
Maximum production of total THOD with 44% conversion of substrate was achieved at 72 h of incubation, after which THOD production
plateaued up to 240 h. THOD production and cell growth increased in parallel with glucose concentration up to 0.3%, after
which cell growth reached its maximum and THOD production did not increase. These results suggested that THODs were not metabolized
by strain PR3. This is the first report of microbial production of 9,10,13- and 9,12,13-THOD from linoleic acid. Journal of Industrial Microbiology & Biotechnology (2000) 25, 109–115.
Received 18 March 2000/ Accepted in revised form 09 June 2000 相似文献
4.
Streptococcus thermophilus is used extensively for industrial fermentation of dairy products. Some strains of S. thermophilus are known to carry plasmids, and many of these plasmids are suspected of encoding low-molecular-weight heat stress proteins
(Hsps) that may aid in survival under stressful conditions. In order to confirm the presence and examine the similarity of
these low-molecular-weight Hsps, genes were identified and sequenced encoding Hsps on plasmids pER16 (4.5 kb), pER35 (10 kb),
and pER36 (3.7 kb) from three different strains of S. thermophilus. The plasmid replication proteins were also sequenced to examine their relatedness. Amino acid sequence comparisons of the
Hsps and of the replication proteins revealed a high degree of identity suggesting a common origin. Heat stress proteins enhance
the viability of bacteria in extreme environments, and the presence of an Hsp encoded on a plasmid may enhance survival of
S. thermophilus under harsh production conditions.
Received: 8 February 2000 / Accepted: 8 March 2000 相似文献
5.
The coffee fermentation microflora were rich and mainly constituted of aerobic Gram-negative bacilli, with Erwinia and Klebsiella genuses at the highest frequencies. The best population increase was observed with lactic acid bacteria and yeasts, whereas
those microorganisms that counted on a pectin medium remained constant during the fermentation step. Qualitatively, lactic
acid bacteria belonged mainly to Leuconostoc mesenteroides species but the others microflora were relatively heterogeneous. The microorganisms isolated on pectin medium were Enterobacteriaceae,
identified as Erwinia herbicola and Klebsiella pneumoniae, not reported as strong pectolytic strains. Throughout coffee fermentation, 60% of the simple sugars were degraded by the
total microflora and not specifically by pectolytic microorganisms.
Received: 21 August 2000 / Accepted: 25 September 2000 相似文献
6.
Stable-isotope-labelled (2H6,18O) 3-hydroxy-3-phenylpropanoic acid, a putative intermediate in the biosynthesis of benzoic acid (BA) and salicylic acid (SA)
from cinnamic acid, has been synthesized and administered to cucumber (Cucumis sativus L.) and Nicotiana attenuata (Torrey). Analysis of the products by gas chromatography-mass spectrometry revealed incorporation of labelling into BA and
SA, but not into benzaldehyde. In a separate experiment, 3-hydroxy- 3-phenylpropanoic acid was found to be a metabolite of
phenylalanine, itself the primary metabolic precursor of BA and SA. These data suggest that cinnamic acid chain shortening
is probably achieved by β-oxidation, and that the proposed “non-oxidative” pathway of side-chain degradation does not function
in the biosynthesis of BA and SA, in cucumber and N. attenuata.
Received: 10 February 2000 / Accepted: 18 April 2000 相似文献
7.
J. Pospíilov g. Entlicher J. Koroucek 《Biochimica et Biophysica Acta (BBA)/General Subjects》1974,362(3):593-597
A receptor glycopeptide for hemagglutinin of the pea (Pisum sativum L.) was isolated from rabbit erythrocytes by the method originally applied for isolation of a receptor glycopeptide from human erythrocytes (Kubánek, J., Entlicher, G. and Kocourek, J. (1973) Biochim. Biophys. Acta 304, 93–102). The receptor isolated from rabbit erythrocytes contains galactose, mannose, N-acetylglucosamine, asparic acid, threonine, serine glutamic acid and glycine in approximate molar ratios of 2:1:3:3:1:1:1:1. It has a minimum molecular weight of about 2000. According to the sequence analysis the following structure has been proposed for the receptor:
About 90% of the receptor-site activity for the pea hemagglutinin is due to the presence of two galactose residues on non-reducing terminals of the saccharide chain in spite of the fact that the pea haemagglutinin is not inhibited by this sugar. 相似文献
Full-size image (1K)
8.
The active efflux system contributing to the solvent tolerance of Pseudomonas putida S12 was characterized physiologically. The mutant P. putida JK1, which lacks the active efflux system, was compared with the wild-type organism. None of 20 known substrates of common
multi-drug-resistant pumps had a stronger growth-inhibiting effect on the mutant than on the wild type. The amount of [14C]toluene accumulating in P. putida S12 increased in the presence of the solvent xylene and in the presence of uncouplers. The effect of uncouplers confirms
the proton dependency of the efflux system in P. putida S12. Other compounds, potential substrates for the solvent pump, did not affect the accumulation of [14C]toluene. These results show that the efflux system in P. putida S12 is specific for organic solvents and does not export antibiotics or other known substrates of multi-drug-resistant pumps.
Received: 15 February 2000 / Received revision: 16 June 2000 / Accepted: 18 June 2000 相似文献
9.
Saayman M van Vuuren HJ van Zyl WH Viljoen-Bloom M 《Applied microbiology and biotechnology》2000,54(6):792-798
The dicarboxylic acid fumarate is an important intermediate in cellular processes and also serves as a precursor for the
commercial production of fine chemicals such as l-malate. Yeast species differ remarkably in their ability to degrade extracellular dicarboxylic acids and to utilise them
as their only source of carbon. In this study we have shown that the yeast Candida utilis effectively degraded extracellular fumarate and l-malate, but glucose or other assimilable carbon sources repressed the transport and degradation of these dicarboxylic acids.
The transport of both dicarboxylic acids was shown to be strongly inducible by either fumarate or l-malate while kinetic studies suggest that the two dicarboxylic acids are transported by the same transporter protein. In
contrast, Schizosaccharomyces pombe effectively degraded extracellular l-malate, but not fumarate, in the presence of glucose or other assimilable carbon sources. The Sch. pombe malate transporter was unable to transport fumarate, although fumarate inhibited the uptake of l-malate.
Received: 15 March 2000 / Received revision: 4 July 2000 / Accepted: 9 July 2000 相似文献
10.
Taurocholic acid transport in Lactobacillus reuteri CRL 1098 was determined. The bile acid is incorporated inside the cells by an active and saturable transport showing a typical
kinetics of Michaelis-Menten with values of K
m
and V
max
of 0.35 mm and 20 mm, respectively.
Received: 30 May 2000/Accepted: 5 July 2000 相似文献
11.
Combined Effect of Bacteriocins on the Survival of Various Listeria Species in Broth and Meat System
Vignolo G Palacios J Farías ME Sesma F Schillinger U Holzapfel W Oliver G 《Current microbiology》2000,41(6):410-416
The antilisterial efficiency of three bacteriocins from lactic acid bacteria, lactocin 705 (produced by L. casei CRL705, 17000 AU/ml), enterocin CRL35 (produced by E. faecium CRL35, 17000 AU/ml), and nisin (2000 IU/ml), was tested in broth, individually and in combination against Listeria monocytogenes and Listeria innocua. Both Listeria species showed an initial decrease in viable counts followed by the regrowth of the survivors after 1 h in the presence of
each bacteriocin. A greater antilisterial effect was observed when the bacteriocins were combined in pairs, maximal inhibition
being reached when nisin was involved. When a mix of the three bacteriocins was used, no survivors were observed after 24
h of incubation. Similar results were obtained when the bacteriocin combinations were tested in a meat system, indicating
that the use of more than one LAB bacteriocin in combination may be effective in preventing the spontaneous emergence of a
bacteriocin-resistant Listeria population.
Received: 17 March 2000 / Accepted: 26 June 2000 相似文献
12.
A recently developed method for analyzing metabolic networks using 13C-labels was employed for investigating the metabolism of a high- and a low-yielding strain of Penicillium chrysogenum. Under penicillin-producing conditions, the flux through the pentose phosphate (PP) pathway in the high- and the low-yielding
strains was estimated to 70 and 66, respectively. When the high-yielding strain was cultivated in a medium without the penicillin
side chain precursor, phenoxyacetic acid, the PP pathway flux was estimated as 71. Thus, in all three experiments, the flux
through the PP pathway was almost constant with an average value of 69 ± 3, and the method therefore allows for a very reproducible
estimation of the PP pathway flux. Phenoxyacetic acid was found to be a source of cytosolic acetyl-CoA and thereby a source
of precursors for the biosynthesis of 2-aminoadipic acid, which is a central amino acid in penicillin biosynthesis. However,
the labeling patterns also indicated the presence of an unrecognized pathway to cytosolic acetyl-CoA.
Received: 20 December 1999 / Received revision: 7 March 2000 / Accepted: 10 March 2000 相似文献
13.
During enrichments to search for soil bacteria that form the volatile ketones, acetone and butanone, we isolated pure cultures
of Pseudomonas aureofaciens, P. fluorescens, and P. putida that excrete the β-keto-acid, 3-oxopentanoate (3-OPA), when grown on heptanoic acid as carbon source. Analysis of 3-OPA used
enzymatic decarboxylation by acetoacetate decarboxylase to yield butanone, which was detected by headspace gas chromatography.
The formation of 3-OPA was strongly dependent on heptanoic acid concentration, the level of oxygen, and the state of growth,
and was not seen with even-chain or other odd-chain fatty acids. Uptake of 3-OPA during stationary phase of growth is probably
related to polyhydroxyalkanoate (PHA) formation in these isolates. A model for formation and release of 3-OPA is proposed.
Received: 28 August 2000 / Accepted: 2 October 2000 相似文献
14.
The effect of sugar concentration on the production of saikosaponins was investigated using a root culture of Bupleurum falcatum L. The formation of the lateral roots, which were induced in the presence of indolebutyric acid, was suppressed as the sugar
concentration was increased. After the lateral root tips had emerged from the inoculated roots, however, high concentrations
of sugar showed no inhibitory effect on the development of the lateral roots. A two-step culture, with 1% sucrose at the beginning
of the culture and addition of 6% sucrose at 14 days, when lateral roots have emerged, greatly improved the productivity,
affording 0.8 g/l of saikosaponin-a and -d.
Received: 28 October 1999 / Revision received: 19 April 2000 / Accepted: 27 April 2000 相似文献
15.
Embryogenic nucellar callus cultures of different Citrus species and cultivars growing in hormone-free medium were transferred to medium containing either sucrose or glycerol as
the only carbohydrate source. Glycerol has been reported to induce further development of Citrus somatic embryos, while in the presence of sucrose they continue to proliferate in an 'undifferentiated' manner. The endogenous
hormone levels of the cultures were evaluated after 2 and 5 days to characterise the initial steps of embryo development.
In most cases, differences among treatments were observed only after 5 days of culture. Higher cytokinin levels were found
in most of the cultures transferred to the glycerol-containing medium. The effect of ageing sweet orange cultures on their
endogenous hormone levels was determined by leaving them in the original culture medium without subculturing for 60 days.
While no changes were observed in the free indoleacetic acid and gibberellin contents, lower levels of abscisic acid and cytokinins
were found in the aged cultures than in those transferred at the normal interval, every 30 days. The endogenous hormone contents
of Citrus callus of different genotypes were compared. Significant differences were observed in the levels of all hormones evaluated,
even when the in vitro ontogeny of the different genotypes was very similar.
Received: 10 February 2000 / Revision received: 25 August 2000 / Accepted: 29 August 2000 相似文献
16.
Sequences from the tuf gene coding for the elongation factor EF-Tu were amplified and sequenced from the genomic DNA of Pirellula marina and Isosphaera pallida, two species of bacteria within the order Planctomycetales. A near-complete (1140-bp) sequence was obtained from Pi. marina and a partial (759-bp) sequence was obtained for I. pallida. Alignment of the deduced Pi. marina EF-Tu amino acid sequence against reference sequences demonstrated the presence of a unique 11-amino acid sequence motif
not present in any other division of the domain Bacteria. Pi. marina shared the highest percentage amino acid sequence identity with I. pallida but showed only a low percentage identity with other members of the domain Bacteria. This is consistent with the concept
of the planctomycetes as a unique division of the Bacteria. Neither primary sequence comparison of EF-Tu nor phylogenetic
analysis supports any close relationship between planctomycetes and the chlamydiae, which has previously been postulated on
the basis of 16S rRNA. Phylogenetic analysis of aligned EF-Tu amino acid sequences performed using distance, maximum-parsimony,
and maximum-likelihood approaches yielded contradictory results with respect to the position of planctomycetes relative to
other bacteria. It is hypothesized that long-branch attraction effects due to unequal evolutionary rates and mutational saturation
effects may account for some of the contradictions.
Received: 21 August 2000 / Accepted: 8 January 2001 相似文献
17.
Mai C Schormann W Milstein O Hüttermann A 《Applied microbiology and biotechnology》2000,54(4):510-514
The storage stability of laccase (EC 1.10.3.2) from the white-rot basidomycete Trametes versicolor in potassium-citrate buffer was enhanced by various phenolic compounds as well as by lignin sulfonate. The highest storage
stability was obtained with phenolics, e.g. phloroglucin and 3,5-dihydroxybenzoic acid; these represent substrates of laccase
which are oxidized slowly because of their relatively high redox potential and which did not precipitate from the solution
within the tested period of time. Sterilization enhanced the stability of laccase but additional stabilization by phenolics
was observed both under sterile and non-sterile conditions. We thus concluded that stabilization occurred not only through
prevention of microbial degradation.
Received: 25 April 2000 / Received revision: 16 June 2000 / Accepted: 18 June 2000 相似文献
18.
Yumoto I Yamazaki K Hishinuma M Nodasaka Y Inoue N Kawasaki K 《Extremophiles : life under extreme conditions》2000,4(5):285-290
Facultatively alkaliphilic Bacillus sp. strain YN-2000 was isolated from an indigo ball. Although the strain has been extensively investigated as a representative
strain of alkaliphilic bacillus, its taxonomic position is not yet known. Morphological, biochemical, and physiological characteristics
and chemotaxonomic properties indicated that the strain was closely related to Bacillus cohnii; this was confirmed by the high homology of the 16S rRNA sequence and the construction of a phylogenetic tree on the basis of the 16S rRNA sequence and DNA–DNA relatedness data. Strain YN-2000 contained a larger amount of unsaturated fatty acids compared
with Bacillus subtilis and the obligate alkaliphile, Bacillus alcalophilus, regardless of its culture pH. When the cells were grown at pH 10, the unsaturated fatty acid content and anteiso-/iso-branched
fatty acid ratio became lower than those at pH 7. This result suggests that membrane fluidity decreases when the cells are
grown at pH 10 compared to those of pH 7. In the cells of strain YN-2000 grown at pH 10, the cell-surface aspect was rougher,
the cell shape was longer, and the cell-surface layer was thicker compared with those of the cells grown at pH 7. The cell-surface
structural change might be related to adaptation to an alkaline environment.
Received: April 6, 2000 / Accepted: May 8, 2000 相似文献
19.
The membrane-bound NADH dehydrogenase of an alkaliphilic Bacillus YN-1 involved in the respiratory chain exhibits reductase activity for hydrogen peroxide and cumene hydroperoxide in the
presence of the 22-kDa component (AhpC) from Amphibacillus xylanus (Koyama et al. Biochem. Biophys. Res. Commun. 247, 659–662). In this study, AhpC-like polypeptide with an apparent molecular
mass of 20 kDa was isolated from the cell-free extract of YN-1. The NADH dehydrogenase exhibited reductase activity for cumene
hydroperoxide in the presence of the purified AhpC-like component from YN-1. It is likely that the NADH dehydrogenase is not
only involved in the respiratory chain, but also functions for scavenging peroxide in the presence of its own endogenous AhpC
component. The enzyme expressed in Escherichia coli as a fusion protein with glutathione S-transferase (GST) showed the NADH dehydrogenase activity as high as the native enzyme
from YN-1. While the fusion protein was unable to reduce cumene hydroperoxide in the presence of AhpC-like protein from YN-1,
the protein obtained by the cleavage treatment of the fusion protein to release GST exhibited the reductase activity as much
as the native enzyme.
Received: 23 May 2000 / Accepted: 26 June 2000 相似文献
20.
Effects of acetic acid and lactic acid on the growth of Saccharomyces cerevisiae in a minimal medium 总被引:1,自引:0,他引:1
N V Narendranath K C Thomas W M Ingledew 《Journal of industrial microbiology & biotechnology》2001,26(3):171-177
Specific growth rates (μ) of two strains of Saccharomyces cerevisiae decreased exponentially (R
2>0.9) as the concentrations of acetic acid or lactic acid were increased in minimal media at 30°C. Moreover, the length of
the lag phase of each growth curve (h) increased exponentially as increasing concentrations of acetic or lactic acid were
added to the media. The minimum inhibitory concentration (MIC) of acetic acid for yeast growth was 0.6% w/v (100 mM) and that
of lactic acid was 2.5% w/v (278 mM) for both strains of yeast. However, acetic acid at concentrations as low as 0.05–0.1%
w/v and lactic acid at concentrations of 0.2–0.8% w/v begin to stress the yeasts as seen by reduced growth rates and decreased
rates of glucose consumption and ethanol production as the concentration of acetic or lactic acid in the media was raised.
In the presence of increasing acetic acid, all the glucose in the medium was eventually consumed even though the rates of
consumption differed. However, this was not observed in the presence of increasing lactic acid where glucose consumption was
extremely protracted even at a concentration of 0.6% w/v (66 mM). A response surface central composite design was used to
evaluate the interaction between acetic and lactic acids on the specific growth rate of both yeast strains at 30C. The data
were analysed using the General Linear Models (GLM) procedure. From the analysis, the interaction between acetic acid and
lactic acid was statistically significant (P≤0.001), i.e., the inhibitory effect of the two acids present together in a medium is highly synergistic. Journal of Industrial Microbiology & Biotechnology (2001) 26, 171–177.
Received 06 June 2000/ Accepted in revised form 21 September 2000 相似文献